# AD 2008-14-14: Auxiliary power unit (APU) - Type: Airworthiness directive - Status: Current - Products: Boeing 747-400 Series and 747-400D Series - Effective: August 21, 2008 - Published: July 17, 2008, 73 FR 40953–40955 - Issued: June 27, 2008 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-15609 - Docket: FAA-2007-0267 (https://www.regulations.gov/docket/FAA-2007-0267) - Project: 2007-NM-245-AD - Registered aircraft: 38 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/9e/a6/9ea6f3e75928be3e8625c2800441a3760a84d7c3b5b21a53dbc9acc26ed9cb86 (from https://www.govinfo.gov/content/pkg/FR-2008-07-17/pdf/E8-15710.pdf) - Federal Register: https://www.federalregister.gov/documents/2008/07/17/E8-15710/airworthiness-directives-boeing-model-747-400-and-747-400d-series-airplanes - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C0128018773DD90C862574890050C0C1.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/2008-14-14 ## Summary We are adopting a new airworthiness directive (AD) for certain Boeing Model 747-400 and 747-400D series airplanes. This AD requires a general visual inspection of the power feeder wire bundle of the auxiliary power unit (APU) where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube. This AD also requires related investigative and corrective actions if necessary. This AD results from a report that the power feeder wire bundle of the APU was found touching the hydraulic system return tube during inspection of an airplane. We are issuing this AD to prevent insufficient clearance between the wire bundle and hydraulic tube that could lead to chafing of the wire bundle, which could cause arcing and a consequent hydraulic fluid fire in an area outside of the smoke detection and fire extinguishing zone; this condition could result in an uncontrolled fire on the airplane. ## The airworthiness directive ### Adoption of the Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: 1. The authority citation for part 39 continues to read as follows: 2. The FAA amends § 39.13 by adding the following new AD: 2008-14-14 Boeing: Amendment 39-15609. Docket No. FAA-2007-0267; Directorate Identifier 2007-NM-245-AD. ### (a) Effective Date (a) This airworthiness directive (AD) is effective August 21, 2008. ### (b) Affected ADs (b) None. ### (c) Applicability (c) This AD applies to Boeing Model 747-400 and 747-400D series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007. ### (d) Unsafe Condition (d) This AD results from a report that the power feeder wire bundle of the auxiliary power unit (APU) was found touching the hydraulic system return tube during inspection of an airplane. We are issuing this AD to prevent insufficient clearance between the wire bundle and hydraulic tube that could lead to chafing of the wire bundle, which could cause arcing and a consequent hydraulic fluid fire in an area outside of the smoke detection and fire extinguishing zone; this condition could result in an uncontrolled fire on the airplane. ### (e) Compliance (e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. ### (f) Inspection and Related Investigative and Corrective Actions (f) Within 24 months after the effective date of this AD, do a general visual inspection of the power feeder wire bundle of the APU where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube, and do all the related investigative and corrective actions as applicable, by accomplishing all of the actions specified in the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007. The related investigative and corrective actions must be accomplished before further flight after the inspection. ### (g) Credit for Actions Done According to Previous Issue of Service Bulletin (g) Actions done before the effective date of this AD in accordance with Boeing Special Attention Service Bulletin 747-24-2257, dated May 18, 2006, are acceptable for compliance with the corresponding requirements of paragraph (f) of this AD. ### (h) Alternative Methods of Compliance (AMOCs) (h)(1) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. ### (i) Material Incorporated by Reference (i) You must use Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007, to do the actions required by this AD, unless the AD specifies otherwise. (1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51. (2) For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. (3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. ## Rule preamble ### Dates This AD is effective August 21, 2008. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of August 21, 2008. ### Addresses For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. ### For further information contact Georgios Roussos, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6482; fax (425) 917-6590. ### Discussion We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Boeing Model 747-400 and 747-400D series airplanes. That NPRM was published in the Federal Register on December 4, 2007 (72 FR 68106). That NPRM proposed to require a general visual inspection of the power feeder wire bundle of the auxiliary power unit (APU) where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation between the wire bundle and hydraulic tube. That NPRM also proposed to require related investigative and corrective actions if necessary. ### Comments We gave the public the opportunity to participate in developing this AD. We considered the three comments received. ### Supportive Comment The commenters Adam W. Rocks and Boeing support the NPRM. ### Request To Revise Applicability Brady J. Mitchell, an employee of Boeing, requests that all Boeing Model 747-400 series airplanes converted from a passenger-to-freighter configuration be excluded from the applicability of the NPRM. Mr. Mitchell states that those airplanes will have new hydraulic tubes and eliminate the possibility of an insufficient clearance or potential chafing condition between the tubes and the power feeder wire bundles of the APU between stations 2040 and 2060. Mr. Mitchell concludes that such a configuration change fulfills the requirements in paragraph (f) of the NPRM. We do not agree. We have reviewed the details of the passenger-to-freighter conversion to which the commenter refers. We have determined that there is not a common configuration for each airplane that is converted. Rather, the details of each conversion are likely to be different from airplane to airplane. Therefore, each conversion configuration needs to be evaluated to ensure the unsafe condition identified in this AD is corrected. For this reason, providing a blanket exception for all airplanes that are converted to a freighter configuration is not appropriate. However, anyone may apply for an alternative method of compliance (AMOC) for relief from the requirements of this AD. Under the provisions of paragraph (h) of this AD, we may consider requests for approval of an AMOC if sufficient data are submitted to substantiate that a passenger-to-freighter configuration change would provide an acceptable level of safety. ### Conclusion We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD as proposed. ### Costs of Compliance There are about 462 airplanes of the affected design in the worldwide fleet. This AD affects 61 airplanes of U.S. registry. The required inspection takes 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the AD for U.S. operators is $4,880, or $80 per airplane. ### Authority for This Rulemaking Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority. We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. ### Regulatory Findings This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that this AD: (1) Is not a “significant regulatory action” under Executive Order 12866, (2) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), and (3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A20WE](https://openairdocs.org/tcds/A20WE): The Boeing Company; names 2 of 14 models: 747-400D Series, 747-400 Series ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 38 (38 by airframe model, 0 by engine model) - Makers: Boeing 38 Models with the most aircraft: - [Boeing 747-446](https://openairdocs.org/model/boeing-747-446): 10 aircraft (airframe model) - [Boeing 747-422](https://openairdocs.org/model/boeing-747-422): 8 aircraft (airframe model) - [Boeing 747-412](https://openairdocs.org/model/boeing-747-412): 5 aircraft (airframe model) - [Boeing 747-409](https://openairdocs.org/model/boeing-747-409): 4 aircraft (airframe model) - [Boeing 747-481](https://openairdocs.org/model/boeing-747-481): 3 aircraft (airframe model) - [Boeing 747-443](https://openairdocs.org/model/boeing-747-443): 2 aircraft (airframe model) - [Boeing 747-438](https://openairdocs.org/model/boeing-747-438): 2 aircraft (airframe model) - [Boeing 747-428](https://openairdocs.org/model/boeing-747-428): 2 aircraft (airframe model) - [Boeing 747-400](https://openairdocs.org/model/boeing-747-400): 1 aircraft (airframe model) - [Boeing 747-451](https://openairdocs.org/model/boeing-747-451): 1 aircraft (airframe model) All 10 models: https://openairdocs.org/ad/2008-14-14/models.md Every aircraft: https://openairdocs.org/ad/2008-14-14/aircraft.md ## Related documents - [Proposed rule FAA-2007-0267](https://openairdocs.org/proposed/FAA-2007-0267): Notice of proposed rulemaking (NPRM), published Dec 4, 2007 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.